Comparison of pathological response of standard chemoradiotherapy versus short course radiotherapy in rectal carcinoma: A pilot study

Neoadjuvant chemoradiation (CRT) is standard of care for locally advanced rectal cancer. However short course radiotherapy (SCRT) was developed for the benefit of a shorter treatment duration and early surgical intervention which also helped in reducing the case burden to the hospital. SCRT is routinely practised in European countries, Indian experience with the SCRT is limited and hence a pilot study was conducted to compare the morphological difference and pathological response between SCRT and CRT. A) Evaluate the morphological changes and pathological response between SCRT and CRT. B) Compare the pathologic response with outcome between SCRT and CRT. All rectal cancer patients in clinical stage II and III diagnosed during 2016 to 2020, who underwent SCRT or CRT were selected. Altered histopathologic findings due to therapy such as tumor cell morphology, necrosis and stromal response along with pathological response between the study groups were compared along with the outcome. Ten (12.6%) patients were subjected to SCRT and 69 (87.4%) patients underwent CRT. Morphological changes such as necrosis was noted in nine (90%) and eight (11.5%) cases in SCRT and CRT group respectively. Pathologic complete response (pCR) was noted in 12 (17.5%) cases of CRT only. Near complete response was seen in one (10%) and 14 (20.5%) cases of SCRT and CRT respectively. Despite lower rates of pCR in SCRT, no difference in survival or outcome was noted between the two study groups. pCR as expected is less in patients who received SCRT, despite this the outcome during follow up was similar in both the groups. Indian data is very limited and large multi-centre studies should be carried as SCRT offers an advantage of early definitive surgical intervention in addition to shorter duration of hospitalisation when compared with CRT.